FWIW, I got a chance to take a closer look at one of the CRC snippets you have on your 8052.com User area and see that it also (like the code posted in this thread) uses only a bit shifted out of the CRC register to determine whether or not to XOR the feedback bits. Whether or not to XOR the feedback bits should be determined by that same bit shifted out of the CRC register XOR'ed with the next shifted bit out of the data. That's what I meant in my other post about not incorporating (XOR'ing) the data into the CRC properly.

I seem to recall having some "standard" CRC test patterns if you are interested in testing for proper CRC operation and standards compliance. I did a brief search for them without success, but will persist if there is any interest. I do also seem to recall running across some test patterns on the internet too.